Degenerative diseases of the arteries such as aneurysms and dissections often necessitate arterial replacement. Conventional open surgery for arterial replacement is associated with significant risk of death or disability and may be especially dangerous for the vascular patient who typically has significant pre-existing surgical risk factors.
Minimally invasive alternatives to open vascular surgery have been developed, chiefly employing endovascular means whereby arterial replacement is performed by placement of an endovascular prosthesis via a remote access point. Such endovascular prostheses are usually comprised of an impervious fabric through which blood flows, preventing contact with the diseased arterial wall. The fabric may be sealed to disease-free arterial wall above and below the diseased segment of artery to be bypassed. These endovascular prostheses have been successfully applied to repair disease of the thoracic and abdominal aorta and peripheral arteries, where tubular prostheses without branches may be employed. A limitation on the applicability of these prostheses has been their inability to repair branched arteries.
Examples of regions of the aorta commonly affected by arterial disease which include branches are the aortic arch, from which the innominate, carotid and subclavian arteries originate, and the proximal abdominal aorta, from which the visceral and renal arteries emerge as side branches. Although grafts have been designed with end branches to accommodate the iliac arteries, no commercially available device exists with side branches to accommodate the thoracic and abdominal aortic branches.
Recently, there have been some attempts at the design of branched prostheses. All of these have inherent problems which have been overcome by the present invention.
For example, U.S. Pat. No. 5,424,765—Tifenbrun et al. discloses a prosthesis with holes custom cut into the sides of the main tubular body prior to surgery based on radiographic measurements of individual patients. These holes must be precisely aligned with the side branch arteries to be replaced. This is often difficult or impossible in actual practice owing to the variability in individual patient anatomy and the difficulty of accomplishing this precise alignment in vivo. Additionally, blood may leak into the segment which is to be excluded by means of this fenestration, rather than flow exclusively into the intended branch vessel.
U.S. Pat. No. 6,428,565 B1—Wisselink discloses a device whereby side branch endografts may be inserted through holes formed in a tubular main body prosthesis. This approach has also been limited by the need for precise alignment of the side-holes with the native arterial branch origins. This is difficult to accomplish in vivo, again owing to the variability of anatomy of individual patients and difficulties in obtaining precise alignment of the prosthesis at the time of implantation. Small measurement errors may result in either longitudinal or circumferential misplacement of these side holes, and this may result in the kinking of the branch endografts as they attempt to reach the native branch vessel.
U.S. patent application No. US 2003/0120333 A1—Ouriel discloses a prosthesis which terminates in multiple end branches which may be connected to branch arteries. This design is limited by crowding of multiple branches within the native aorta which may lead to radiographic confusion in their identification and limit their ability to be manipulated within a confined space. In addition, the necessary use of multiple long sheets of small tubular conduits may be prone to thrombosis and graft failure. The multiple end branches may also be prone to kinking as the end branches interweave on their paths to the various end arteries. As each of the end branches is deployed each successive branch will be more difficult to maneuver in the crowded lumen of the aorta.